Manufacture of reflecting lamps



' July 1, 1941. c. BIRDSEYE E'l'AL MANUFACTURE OF REFLECTING LAMPS Filed Dec. 2, 1937 2 Sheets-Sheet 1 July 1, 1941. c. BIRDSEYE ETAL MANUFACTURE OF REFLECTING LAMPS 2 Sheets-Sheet 2 Filed Dec 2 1937 npenfor Z? particular field of use in Patented July 1, 1941 MANUFACTURE OF REFLECTING LAMPS Clarence Birdseye and assignors, b Birdseye Electric Mass, a corporation Pincus Deren, Gloucester, y mesne assignments, to

Corporation, 01' Massachusetts Gloucester,

Application December 2, 1937, Serial No. 177,780

14 Claims.

to the manufacture of es or the like and has a the production of electric lamp bulbs with an inner metallic reflecting coating. While the invention has broader applications, for purposes of illustration it will be discussed in its adaptation to that field.

In producing lamp bulbs having a reflecting metallic coating upon selected areas of their inner walls, it is the practice to coat substantially the entire inner surface of the bulb by depositing metallic silver or the like from a solution or by vaporizing metal in the partially evacuated bulbs. Subsequently the metal coating is removed from those parts of the bulb where it is not desired. For example, in a bulb intended for direct lighting the metallic coating is removed from the rounded end of the bulb up to substantially the line of maximum diameter. In this operation it is of great importance that metal coated areas shall be defined by a sharp, clean-cut line, and that this line shall be accurately located in the bulb in accordance with the optical effect desired. It is also essential that the retained coating shall be in no way damaged or impaired in the removing operation. One commercial method of removing the metallic coating has been to insert in the bulb a pair of rotary scraping tools arranged centrifugally to follow the contour of the bulb and to travel longitudinally therein. This procedure involves presenting the scraping tools to the individual bulbs and is consequently not suited for production on a large scale. It also introduces an objectionably high factor of breakage into the manufacturing process.

The general object of the present invention is to solve these difliculties and to make available an economical process for the removal of metallic coating from the interior of a number of bulbs simultaneously in a rapid and accurate manner. We have discovered that this may be achieved by filling the coated bulbs to the desired level with a suitable solvent solution, supplied with certain important precautions. The solvent or acid is then permitted to dissolve the metal of the coating up to the desired line, and then the resulting solution is removed, again with proper precautions to avoid impairing the retained coating.

The invention includes within its scope im- This invention relates metallic coated bulbs, tub

proved apparatus for handling a single bulb Or a 150 large number of bulbs simultaneously. In dealing with a single bulb, as in dealing simultaneously with a large number of bulbs, it is important to supply a measured charge of solvent to the coated bulb and to predetermine the.

volume of this charge in exact accordance with the level to which the coating is to be removed. The apparatus of my invention accordingly includes a charge measuring receptacle which may be filled rapidly to overflowing from a suitable reservoir and from which the charge is then adapted to be transferred by gravity to the bulb. It is also of extreme importance that the solvent charge shall be delivered to the bulb without any splashing and in a condition substantially free from air bubbles which are likely to free particles of solvent in rising to the surface, which particles tend to form pinholes in the retained coating. These difliculties are avoided in accordance with the present invention by delivering the solvent charge to the bottom of the bulb in an area trapped for air bubbles and through an outlet designed to prevent splashing.

The removal of the solvent from the bulb after it has dissolved the coating in the desired area, presents similar dimculties as those involved in delivering the charge and in addition it will be obvious that all possibility must be avoided of permitting drops of solvent torun down the surface of the bulb upon the coating which is to be retained. These requirements are met in accordance with the present invention by the provision of a suction tube arranged to extract the acid solution cleanly from the bottom of the bulb without in any way disturbing it. The result is that the coating is removed accurately to a cleancut liquid level line lying in a horizontal plane.

The process and apparatus of our invention are applicable to the treatment of a large number of bulbs or similar articles handled as a group. To this end an important feature of the invention consists in a support or holder for a group of bulbs and a corresponding group of nozzles for supplying and removing solvent arranged for relative movement with respect of the support so that all the nozzles may be inserted in the bulbs simultaneously or in ordered sequence. For example, the support or holder may be provided with gauges for accurately positioning one hundred bulbs or any desired number of bulbs in spaced relation and upright position and, when loaded, may be elevated to insert overhanging nozzles into the bulbs and maintain this operative relation during thesteps of supplying and removing the solvent.

In this connection another important feature of the invention consists in a series of chargemeasuring devices arranged to be filled to overflowing from a single source of supply. These elements are so arranged that overflow solvent from the last measuring device or the series is utilized to time the operation or means for shutting oi! the flow or further solvent from the sources or supply for the ensuing portion of the cycle of operations.

Another important feature of our invention relates more particularly to the removal of used solvent from the bulbs 01 the group. It is essential that the used solvent should be completely drained from every bulb regardless of unavoidable variations in the solvent level of the individual bulbs during the draining process. If suction alone is relied upon, a lowering of the solvent level in a single bulb below the suction outlet may admit air to the whole system and so impair its uniform efliciency. The present invention, however, contemplates initiating the draining operation by suction and completing it from each bulb by independent syphon action. To this end the apparatus includes a conduit located below the bulbs and independent syphon tubes leading from the bottom of each bulb to this conduit.

The process of our invention is characterized by recirculating the solvent after use to the reservoir supplying the system so that the solvent may be used over and over again until the amount of metal it contains makes renewal expedient. This characteristic of our process and apparatus for carrying it out are believed to be broadly novel in the art.

These and other features and characteristics of the inventionfwill be best understood and appreciated from the following description of a preferred embodiment of apparatus adapted for use in carrying out the process of our invention, shown more or less diagrammatically in the accompanying drawings in which- Fig. 1 is a diagrammatic view of the apparatus as adapted to the simultaneous handling of a group of bulbs,

Fig. 2 is a view in side elevation partly in sec tion of one unit of the apparatus,

Fig. 3 is a view in perspective of the bobbin used in the acid delivering nozzle,

Fig. 4 is a sectional view of the nozzle on the line l4 of Fig. 2,

Fig. 5 is a fragmentary plan view of the bulb carrier and,

Fig, 6 is a view in longitudinal section and on an enlarged scale showing the solvent delivering nozzle in position in a bulb.

It will be convenient first to describe a single unit of the apparatus as illustrated in Figs. 2-6 and then to describe the apparatus in which the units are incorporated in adapting it to treat simultaneously a plurality 01 metal coated bulbs. Each unit comprises a support it having a series of radially adjustable gauges ii for centering and supporting a bulb in upright position. Each gauge has an upstanding flexible arm for engaging a bulb substantially about its line of maximum diameter. The gauges may be adjusted to center the bulb in the desired location or for the accommodation of larger or smaller bulbs. The carrier includes a vertical wall from which projects a bracket having a pair of spring clamping arms H which engage the neck of the bulb and maintain it accurately in upright position. The bulb is thus supported from beneath, gauged at four points spaced about its line of maximum diameter and held about the neck.

Above the bulb station .is supported an open filling receptacle I! having a long downwardly extending hollow stem l5 which is engaged by stationary vertically spaced supporting clamps It, the receptacle being adiustably supported in this manner. The lower portion of the stem I5 is surrounded by an outside tube l8 0! substantially larger diameter, being held in spaced concentric relation to the hollow stem by four spacer strips I1 having outtumed ends arranged to hook over the upper edge of the outside tube l8 and elongated body portions which extend downwardly for a substantial distance between the two tubes. A suction tube IQ of smaller diameter is arranged concentrically within the hollow stem l5 and this passes up through the open receptacle H where it is bent at right angles and connected with a vacuum system.

Surrounding the lower end of the suction tube 19, as best shown in Fig. 6, is a bobbin 20 of spring metal upon which is wound a porous packing of spun glass or other flexibl material suitable to form in effect a filter to absorb the impact of solvent solution flowing down the stem I5, allowing it to seep gently into the bulb without splashing and with the removal of air bubbles as completely as possible. It will be noted also that the lower end of the stem 15 is slightly above the lower end of the outside pipe i8 so that the latter acts as a trap for any air bubbles which may pass through the packing 2|, directing them upwardly inside the tube l8 rather than permitting them to rise to the surface of the unconfined solvent solution in the bulb. The lower end of the suction tube l9 extends slightly further than the lower end of the hollow stem lb or of the outside tube 18, being located substantially in contact with the bottom of the bulb so as to remove cleanly the solvent solution at the proper point in th cycle of operations.

Above the filling receptacle M is located a measuring device 24, herein shown as of the general formof a pipette having a downwardly extending tube 25 provided with a rotary shutoif valve 26. The stem of the shutoff valve is provided with a pinion 21 which is engaged between a pair of horizontal moving racks 28. The movement of these racks in opposite directions is utilized to open the valve 26 when the measured charge has been accumulated, and it is desired to deliver it to the filling receptacle, M. The tube 25 is extended below the shutoif valve 26 and provided at its discharge end with a porous filter 29. The body of the measuring device is shown as containing a plurality of spheres 30 which may be added or removed to regu ate the volume of the charge without in any way interfering with its passage. The measuring device 24 is supplied with acid solution through a supply pipe 32 having a downwardly extending branch 3| which enters the upper end of the measuring device.

The unit above described may be employed tc remove a metal coating from the interior of 2 bulb 22 which has been properly located in lim with the hollow stem I5 and moved upwardl: thereon until the end of the suction pipe I9 prac' tically engages the bottom of the bulb. With thi shutoff valve 26 closed the measuring device 2 is filled to overflowing by the supply pipe 32 Flow through the supply pipe is then cut oi and the shutoif valve 28 opened whereupon th measured charge of acid solution flows by grav ity into the filling receptacle i l. The shutoi valve 26 may then be immediately closed and th operation of refilling the measuring device be gun while the acid solution delivered to the re ceptacle I4 passes down the hollow stem IS an fills the metal-coated bulb 22 up to the desired predetermined level. The metal coating is immediately dissolved up to this line and the acid containing the removed metal in solution may now be removed from the suction pipe l9. The treated bulb may now be removed from its station and washed and will retain its metal coating intact above the level of the acid charge formerly contained therein.

Having described a single unit, we shall now proceed to a description of the assembled apparatus adapted for treating simultaneously a sub-.

stantial number of bulbs as a group.

Referring particularly to Fig. 1 the carrier or holder l comprises a plate or table, which in practice is equipped with gauge fingers and clamps like those shown in Fig. 2 for holding a series of bulbs accurately in spaced relation and in upright position. The illustrated appa-' ratus has a capacity for twelve bulbs and for the sake of clearness the gauge fingers and clamps are omitted in this figure. Any suitable mechanical means may be provided for raising the carrier it from its lower loading position to an elevated position in which the solvent supplying and removing nozzles lead down into the bulbs to a position adjacent the bottomv thereof Each of the nozzles is organized as shown in Figs. 2 and 6, that is to say, it includes an inner suction tube l9, a larger concentric supply pipe l5 and a still larger air-trap l5 spaced from the supply tube and open at its upper end. The tube l5 leads downwardly from an open filling receptacle l4 and this in turn is arranged to be supplied from a charge-measuring device 24. The charge-measuring devices are supplied by a horizontal supply pipe 32 from which they may be suspended, the arrangement being such that solvent flowing along the supply pipe 32 will fill one charge-measuring device 24 after another to overflowing. When the last charge-measuring device of the series has been thus filled overflow solvent passes out of the down turned end of the supply pipe 32 into an overflow device 42 from whence it passes downwardly and is collected in an overflow receptacle 45.

The solvent for filling the measuring device 24 is drawn from a reservoir 35 located in an elevated position so that the liquid solvent may flow by gravity to the bulbs. The reservoir 35 has an outlet pipe 36 leading from its bottom upwardly through a shutoif valve 31 to an intermediate receptacle 38. The receptacle 38 is located at a level below the reservoir 35 so that it will be filled by syphon action when flow has once been started from a full reservoir. A syphon discharge tube 39 leads from the intermediate receptacle 38 to a filling receptacle H which discharges directly into the supply pipe 32. A shutoff valve 40 is located in the long leg of the syphon tube 39 and this valve is electrically controlled so that it may be closed when all of the charge-measuring devices 24 have been filled and overflow solvent begins to enter the overflow device 42. To this end a pair of bare terminals 43 extend into the overflow device beneath the overflow outlet of the supply pipe 32. These terminals lead to a relay box 44 which is connected to a solenoid box 34 organized to efiect closing of the shutoif valve 40 when the solvent, which is an electrolytic solution, flows across the ends of the terminals 43. This permits the refilling oi the intermediate receptacle 38 from the reservoir 35 immediately after the charge measuring desolvent shall be delivered to these devices after the discharge from them has been begun and that the supply pipe 32 is drained oi. all surplus supply of solvent which might otherwise reach the charge measuring devices.

Upon leaving the overflow device 42 the overflow solvent passes downwardly to an overflow receptacle 45 where it is accumulated in readiness to be returned to the reservoir 35 when the latter is to be refilled. For this purpose a suction discharge pipe 46, provided with a valve 41, is arranged to extend into proximity with the bottom of the receptacle, 45 and is connected through a pipe 48 with the reservoir 35. When the valve 47 is opened and the reservoir 35 put into communication with the suction system of the apparatus, whatever overflow solvent has accumulated in the receptacle 45 is drawn up through the pipes 46 and 48 to the reservoir 35.

As already noted the outlet of each charge measuring device 25 is provided with a valve 26. These valves are arranged in horizontal alignment and are each provided with a pinion 27 engaged between a. pair of racks 28 arranged to be moved equally and oppositely by any convenient controlling device such as a lever 14. When all of the charge measuring devices 23 have been filled, as has been explained, the operator mayswing the lever 14 to open all the valves 25, whereupon the measured charges are all released and flow downwardly into the filling receptacles i4 and from them through the discharge pipes i5, rising to the calculated predetermined level in the bulbs.

If the bulbs have a coating of silver a solvent comprising nitric and nitrous acids, for example, will remove the coating cleanly and completely within an interval of two or three minutes up to the liquid level of the solvent charge contained in the bulb. When this has occurred the used acid charge is removed from the bulbs by the means now to be described. As already noted, each of the nozzles includes a suction tube l9 which extends slightly beyond the end of the nozzle, coming substantially into contact with the bottom of the bulb, as best shown in Fig. 6. Each tube i9 is extended upwardly through the filling receptacle l4 and then outwardly and downwardly to a. trunk duct 52 which has a valve 63 and extends through a down-turned band to an intermediate receptacle Bl. The intermediate receptacle Si is connected through a pipe 64 having a. valve 65 to the bottom of a large collecting tank 55. It will be noted that the trunk line duct 52 is located at a level below the bulb support it]. This feature is of importance because the draining of the bulbs is to be completed by V a syphon action as will be presently explained.

vices 24 are filled. It also insures that no further The apparatus includes a system of suction piping which in Fig.- 1 is represented by a single heavy line. One branch of the suction system includes the pipe 5i which is shown as leading from the collecting tank 55 upwardly and toward the right, extending to a vacuum pump not shown. The pipe 5i is connected through a branch and valve 54 to a, pipe 52 which extends into the top of the reservoir 35. Accordingly, when it is desired to refill the reservoir 35 the valve 54 may be opened and the valve 3! closed. Under these conditions the reservoir 35 is subjected to suction and solvent from the receiving tank 50 is drawn upwardly thereto. The pipe 52 has a short branch provided with a valve 53 which may be opened after the reservoir has been filled, thus admitting air to the reservoir when it is desired to draw solvent therefrom through the outlet pipe 36.

The pipe 5i is also provided with a valve 15 and a vent having a valve 55. when solution is to be delivered to the collecting tank 50 in the normal operation of the apparatus the valve 15 .is closed and the valve 55 open, thus venting the tank 50.

The other branch of the suction system includes a pipe 51 which extends upwardly from the intermediate receptacle 6| and is connected through a transverse branch and valve 59 to a pipe 56 leading into the intermediate receptacle 3!. The pipe 51 is also provided with a valve 60 at a point below its branch leading to the pipe 59, By opening the valve 60 the lower intermediate receptacle BI may be placed undersuction, Then by opening. the valve 63 each one of the suction pipes I9 is brought into the system and acid is sucked up from the bottom of each bulb and delivered to the trunk line duct 62. As soon as the solvent has been carried over the bend of any suction pipe IS a syphon action is initiated independently in each bulb and this continues until the solvent has been completely withdrawn from each bulb independently of what is happening in any of the other bulbs. On account of this characteristic the danger of a short or broken suction tube impairing the whole solvent removing operation is eliminated.

The pipe 51 is connected by a branch having a valve 59 with a pipe 56 leading to the intermediate receptacle 38. By opening the valve 59 and closing the valve to the receptacle 38 may be placed under suction and flow of acid started through the outlet pipe 36 and over the bend of the syphon connection therein. The pipe 56 has also a vent outlet with a valve 53 by opening which the receptacle 38' may be vented when solvent is to be drawn therefrom. The pipe 51 is provided also with a vent outlet having a valve 16 which may be opened to vent the receptacle 6i when necessary in the operation of the apparatus.

The nature of the solvent employed will depend upon the character of the metal with which the bulbs are coated. For example, in dissolving a silver coating 30% nitric acid with a small amount of lower oxides present is entirely satisfactory, while an alkaline solvent may be employed to dissolve an aluminum coating. In any case the suction removal of the solvent has the beneficial effect of removing. also solvent vapor which might otherwise impair the retained coat It will be understood that the apparatus herein described represents only one type suitable for carrying out the process of our invention and that other forms of apparatus would serve as well. In many of its aspects, moreover, our new process may be employed in removing metallic coating from bulbs presented in inverted or inclined positions.

Having thus disclosed our invention and described one manner of putting it into efiect, what we claim as new and desire to secure by Letters Patent is:

1. Apparatus for removing metallic coating from limited areas within lamp bulbs, comprising means for supporting a plurality of metal coated bulbs at substantially the same level, a reservoir for solvent solution, and means for introducing individually measured charges of solvent solution from said reservoir as a common source of supply into all of said bulbs for dissolving the metal coating up to a predetermined level and for removing the charges after the coating has been dissolved up to the level 0! the charges.

2. Apparatus for removing metallic coating from limited areas within lamp bulbs, comprisin means for supporting a plurality of metal coated bulbs in upright position, a reservoir for solvent solution, a charge-measuring receptacle located above each bulb, means for filling said receptacles with a liquid solvent from the reservoir as a common source of supply, and means for controlling the discharge of the solvent by said receptacles to said bulbs. V

3. Apparatus for removing metallic coating from limited areas within lamp bulbs, comprising a carrier for a plurality of metal coated bulbs, corresponding charge-measuring receptacles located in line with the bulbs and having discharge tubes, and a reservoir for solvent solution communicating with all oi said receptacles, the carrier being movable in a predetermined path to introduce said tubes simultaneously into all the bulbs on the carrier.

4. Apparatus for removing an internal metallic coating from selected areas in lamp bulbs, comprising means for supporting a group of metal coated bulbs, an acid reservoir, an intermediate receptacle, means for distributing acid from said intermediate receptacle to the respective bulbs of the group including a series of charge-measuring devices, and means for closing and refilling said intermediate receptacle from the reservoir while the charge-measuring devices are discharging to the bulbs.

5. Apparatus for removing an internal metallic coating from selected areas in lamp bulbs, comprisingmeans for supporting a group or metal coated bulbs side-by-side at a predetermined level, an acid reservoir, an acid receiver, means for delivering a measured charge from the reservoir to each bulb of the group to dissolve a predetermined portion of its metallic coating, and means for discharging said charges from the bulbs into said receiver.

6. Apparatus for removing an internal metallic coating from selected areas in lamp bulbs, comprising means for supporting a group of metal coated bulbs, a reservoir for solvent solution, a series of initially closed charge-holding devices in connection with the reservoir and arranged to deliver solvent to the individual bulbs of the group, means for filling all or said devices with solvent and means for simultaneously opening all of said devices for delivering measured charges of solvent to all the bulbs.

7. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a metal-coated bulb, a filling receptacle, a delivery tube leading from the receptacle into a bulb on the support, and a concentric tube of larger diameter surrounding a part of the delivery tube and serving to trap air bubbles in the solution delivered by the delivery tube to the bulb.

8. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a bulb, a delivery tube leading into a bulb on the support, a suction tube of smaller diameter located within the delivery tube, and porous packing filling the space between the two tubes at outlet end of said delivery tube.

9. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a bulb, a solvent delivery tube leading into a bulb on the support, a suction tube located within the delivery tube, and an open ended air trap located in the bulb and surrounding the delivery tube.

10. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a bulb, a supply pipe for electrolytic solvent solution, a charge-measuring device connected to said supply pipe and arranged to discharge into a bulb on said support, an overflow chamber having open circuit terminals arranged to be connected by overflow of the electrolytic solution, and controlling means operated by the circuit thus closed for limiting flow of solvent in the supply pipe.

11. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a group of metal-coated bulbs, means for delivering a measured charge of solvent to each bulb to dissolve a predetermined portion of its metallic coating, and a solvent removing system including a suction tube for each bulb and a trunk line conduit located below said bulbs and into which said suction tubes discharge with independent syphon action.

12. Apparatus of the class described for removing predetermined areas or metallic coating within lamp bulbs, comprising a support for a group of metal-coated bulbs, means for delivering a measured charge of solvent to each bulb of the group, a conduit located below said bulbs, and an independent syphon tube leading from the bottom of each bulb to said conduit whereby the solvent charge maybe drawn from each bulb independently of every other bulb on the support.

13. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a group of bulbs, a solvent reservoir, a charge measuring device for each bulb arranged to be supplied from said reservoir, means for overiilling said devices from the reservoir, means for collecting used solvent from the bulbs, and means for returning to the reservoir both used solvent and overflow solvent from said receptacle.

14. Apparatus of the class described for removing predetermined areas of metallic coating within lamp bulbs, comprising a support for a group of metal-coated bulbs, and means for supplying solvent to the metal-coated bulbs on the support including a charge-measuring device for each bulb, a solvent reservoir communicating with each of said devices, and means for automatically shutting off such communication when all of said devices have been filled.

CLARENCE BIRDSEYE. PINCUS DEREN. 

